OLED display architecture

ABSTRACT

A device that may be used as a multi-color pixel is provided. The device has a first organic light emitting device, a second organic light emitting device, a third organic light emitting device, and a fourth organic light emitting device. The device may be a pixel of a display having four sub-pixels. The first device may emit red light, the second device may emit green light, the third device may emit light blue light and the fourth device may emit deep blue light. The device includes a first device plane and a second device plane. The first device plane comprises a plurality of the first organic light emitting device and a plurality of the second organic light emitting device. The second device plane comprises a plurality of at least one of the third organic light emitting device and the fourth organic light emitting device. The planes of the first and second device planes are parallel. The second device plane is transposed from the first device plane in a direction perpendicular to the planes of the first and second device planes. The first and second device planes are superposed.

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/565,115 titled Novel OLED Display Architecture, filed Sep.23, 2009, which claims priority to and benefit under 35 U.S.C. §119(e)to U.S. Provisional Application No. 61/101,757, filed Oct. 1, 2008, thedisclosures of which are herein expressly incorporated by reference intheir entirety.

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, The University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to organic light emitting devices, andmore specifically to the use of both light and deep blue organic lightemitting devices to render color.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for organic emissive molecules is a full color display.Industry standards for such a display call for pixels adapted to emitparticular colors, referred to as “saturated” colors. In particular,these standards call for saturated red, green, and blue pixels. Colormay be measured using CIE coordinates, which are well known to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the structure of Formula I:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processable” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

A device that may be used as a multi-color pixel is provided. The devicehas a first organic light emitting device, a second organic lightemitting device, a third organic light emitting device, and a fourthorganic light emitting device. The device may be a pixel of a displayhaving four sub-pixels.

The first organic light emitting device emits red light, the secondorganic light emitting device emits green light, the third organic lightemitting device emits light blue light, and the fourth organic lightemitting device emits deep blue light. The peak emissive wavelength ofthe fourth device is at least 4 nm less than that of the third device.As used herein, “red” means having a peak wavelength in the visiblespectrum of 600-700 nm, “green” means having a peak wavelength in thevisible spectrum of 500-600 nm, “light blue” means having a peakwavelength in the visible spectrum of 400-500 nm, and “deep blue” meanshaving a peak wavelength in the visible spectrum of 400-500 nm, where“light” and “deep” blue are distinguished by a 4 nm difference in peakwavelength. Preferably, the light blue device has a peak wavelength inthe visible spectrum of 465-500 nm, and “deep blue” has a peakwavelength in the visible spectrum of 400-465 nm

The first, second, third and fourth organic light emitting devices eachhave an emissive layer that includes an organic material that emitslight when an appropriate voltage is applied across the device. Theemissive material in each of the first and second organic light emissivedevices is a phosphorescent material. The emissive material in the thirdorganic light emitting device is a fluorescent material. The emissivematerial in the fourth organic light emitting device may be either afluorescent material or a phosphorescent material. Preferably, theemissive material in the fourth organic light emitting device is aphosphorescent material.

The first, second, third and fourth organic light emitting devices mayhave the same surface area, or may have different surface areas. Thefirst, second, third and fourth organic light emitting devices may bearranged in a quad pattern, in a row, or in some other pattern.

The device may be operated to emit light having a desired CIE coordinateby using at most three of the four devices for any particular CIEcoordinate. Use of the deep blue device may be significantly reducedcompared to a display having only red, green and deep blue devices. Forthe majority of images, the light blue device may be used to effectivelyrender the blue color, while the deep blue device may need to beilluminated only when the pixels require highly saturated blue colors.If the use of the deep blue device is reduced, then in addition toreducing power consumption and extending display lifetime, this may alsoallow for a more saturated deep blue device to be used with minimal lossof lifetime or efficiency, so the color gamut of the display can beimproved.

The device may be a consumer product.

A first device is provided. The device includes a plurality of pixels,wherein each pixel includes an R sub-pixel, a G sub-pixel, a B1sub-pixel and a B2 sub-pixel. Each R sub-pixel comprises a first organiclight emitting device that emits light having a peak wavelength in thevisible spectrum of 580-700 nm, further comprising a first emissivelayer having a first emitting material. Each G sub-pixel comprises asecond organic light emitting device that emits light having a peakwavelength in the visible spectrum of 500-580 nm, further comprising asecond emissive layer having a second emitting material. Each B1sub-pixel comprises a third organic light emitting device that emitslight having a peak wavelength in the visible spectrum of 400-500 nm,further comprising a third emissive layer having a third emittingmaterial. Each B2 sub-pixel comprises a fourth organic light emittingdevice that emits light having a peak wavelength in the visible spectrumof 400 to 500 nm, further comprising a fourth emissive layer having afourth emitting material. The third emitting material is different fromthe fourth emitting material. The peak wavelength in the visiblespectrum of light emitted by the fourth organic light emitting device isat least 4 nm less than the peak wavelength in the visible spectrum oflight emitted by the third organic light emitting device.

The first device includes a first device plane and a second deviceplane. The first device plane comprises a plurality of the first organiclight emitting device and a plurality of the second organic lightemitting device. The second device plane comprises a plurality of atleast one of the third organic light emitting device and the fourthorganic light emitting device. The planes of the first and second deviceplanes are parallel. The second device plane is transposed from thefirst device plane in a direction perpendicular to the planes of thefirst and second device planes. The first and second device planes aresuperposed.

In one embodiment, the second device plane comprises a plurality of thethird organic light emitting device, and a plurality of the fourthorganic light emitting device.

In one embodiment, the first device plane comprises a plurality of thefirst organic light emitting device, a plurality of the second organiclight emitting device, and a plurality of the third organic lightemitting device. The second device plane comprises a plurality of thefourth organic light emitting device.

In one embodiment, the first device plane comprises a plurality of thefirst organic light emitting device, a plurality of the second organiclight emitting device, and a plurality of the fourth organic lightemitting device. The second device plane comprises a plurality of thethird organic light emitting device.

Preferably, at least one of the first and second device planes each hasa fill factor of at least 30%.

Preferably, the first device is configured such that the first deviceplane is closer to a viewing direction than the second device plane.

The first device may be a display panel. The first device may be aconsumer device.

In one preferred embodiment, the first, second and third emittingmaterials are phosphorescent, and the fourth emitting material isfluorescent. In one preferred embodiment, the first and second emittingmaterials are phosphorescent, and the third and fourth emittingmaterials are fluorescent. A variety of other combinations of emittingmaterial types may be used, such as where the first, second, third andfourth emitting materials are phosphorescent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows a rendition of the 1931 CIE chromaticity diagram.

FIG. 4 shows a rendition of the 1931 CIE chromaticity diagram that alsoshows color gamuts.

FIG. 5 shows CIE coordinates for various devices.

FIG. 6 shows various configurations for a pixel having four sub-pixels.

FIG. 7 shows two different configurations providing two device planes.

FIG. 8 shows a first way to split R, G, B1 and B2 devices between twodevice planes.

FIG. 9 shows a second way to split R, G, B1 and B2 devices between twodevice planes.

FIG. 10 shows a third way to split R, G, B1 and B2 devices between twodevice planes.

FIG. 11 shows a device architecture for a R, G, B1 and B2 devices splitbetween two device planes having a common electrode between the twodevice planes.

FIG. 12 shows a device architecture for a R, G, B1 and B2 devices splitbetween two device planes having a passivation layer between the twodevice planes.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, and a cathode 160. Cathode 160 is acompound cathode having a first conductive layer 162 and a secondconductive layer 164. Device 100 may be fabricated by depositing thelayers described, in order. The properties and functions of thesevarious layers, as well as example materials, are described in moredetail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporatedby reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition WPM, such as described in U.S. Pat. No. 6,337,102 to Forrestet al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. patent application Ser. No. 10/233,470, which is incorporated byreference in its entirety. Other suitable deposition methods includespin coating and other solution based processes. Solution basedprocesses are preferably carried out in nitrogen or an inert atmosphere.For the other layers, preferred methods include thermal evaporation.Preferred patterning methods include deposition through a mask, coldwelding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819,which are incorporated by reference in their entireties, and patterningassociated with some of the deposition methods such as ink jet and OVJD.Other methods may also be used. The materials to be deposited may bemodified to make them compatible with a particular deposition method.For example, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, televisions, billboards, lights forinterior or exterior illumination and/or signaling, heads up displays,fully transparent displays, flexible displays, high resolution monitorsfor health care applications, laser printers, telephones, cell phones,personal digital assistants (PDAs), laptop computers, digital cameras,camcorders, viewfinders, micro-displays, vehicles, a large area wall,theater or stadium screen, or a sign. Various control mechanisms may beused to control devices fabricated in accordance with the presentinvention, including passive matrix and active matrix. Many of thedevices are intended for use in a temperature range comfortable tohumans, such as 18 degrees C. to 30 degrees C., and more preferably atroom temperature (20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, aromatic group, and heteroaryl are known tothe art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32,which are incorporated herein by reference.

One application for organic emissive molecules is a full color display,preferably an active matrix OLED (AMOLED) display. One factor thatcurrently limits AMOLED display lifetime and power consumption is thelack of a commercial blue OLED with saturated CIE coordinates withsufficient device lifetime.

FIG. 3 shows the 1931 CIE chromaticity diagram, developed in 1931 by theInternational Commission on Illumination, usually known as the CIE forits French name Commission Internationale de l'Eclairage. Any color canbe described by its x and y coordinates on this diagram. A “saturated”color, in the strictest sense, is a color having a point spectrum, whichfalls on the CIE diagram along the U-shaped curve running from bluethrough green to red. The numbers along this curve refer to thewavelength of the point spectrum. Lasers emit light having a pointspectrum.

FIG. 4 shows another rendition of the 1931 chromaticity diagram, whichalso shows several color “gamuts.” A color gamut is a set of colors thatmay be rendered by a particular display or other means of renderingcolor. In general, any given light emitting device has an emissionspectrum with a particular CIE coordinate. Emission from two devices canbe combined in various intensities to render color having a CIEcoordinate anywhere on the line between the CIE coordinates of the twodevices. Emission from three devices can be combined in variousintensities to render color having a CIE coordinate anywhere in thetriangle defined by the respective coordinates of the three devices onthe CIE diagram. The three points of each of the triangles in FIG. 4represent industry standard CIE coordinates for displays. For example,the three points of the triangle labeled “NTSC/PAL/SECAM/HDTV gamut”represent the colors of red, green and blue (RGB) called for in thesub-pixels of a display that complies with the standards listed. A pixelhaving sub-pixels that emit the ROB colors called for can render anycolor inside the triangle by adjusting the intensity of emission fromeach sub-pixel.

The CIE coordinates called for by NTSC standards are: red (0.67, 0.33);green (0.21, 0.72); blue (0.14, 0.08). There are devices having suitablelifetime and efficiency properties that are close to the blue called forby industry standards, but remain far enough from the standard blue thatthe display fabricated with such devices instead of the standard bluewould have noticeable shortcomings in rendering blues. The blue calledfor industry standards is a “deep” blue as defined below, and the colorsemitted by efficient and long-lived blue devices are generally “light”blues as defined below.

A display is provided which allows for the use of a more stable and longlived light blue device, while still allowing for the rendition ofcolors that include a deep blue component.

This is achieved by using a quad pixel, i.e., a pixel with four devices.Three of the devices are highly efficient and long-lived devices,emitting red, green and light blue light, respectively. The fourthdevice emits deep blue light, and may be less efficient or less longlived that the other devices. However, because many colors can berendered without using the fourth device, its use can be limited suchthat the overall lifetime and efficiency of the display does not suffermuch from its inclusion.

A device is provided. The device has a first organic light emittingdevice, a second organic light emitting device, a third organic lightemitting device, and a fourth organic light emitting device. The devicemay be a pixel of a display having four sub-pixels. A preferred use ofthe device is in an active matrix organic light emitting display, whichis a type of device where the shortcomings of deep blue OLEDs arecurrently a limiting factor.

The first organic light emitting device emits red light, the secondorganic light emitting device emits green light, the third organic lightemitting device emits light blue light, and the fourth organic lightemitting device emits deep blue light. The peak emissive wavelength ofthe fourth device is at least 4 nm less than that of the third device.As used herein, “red” means having a peak wavelength in the visiblespectrum of 600-700 nm, “green” means having a peak wavelength in thevisible spectrum of 500-600 nm, “light blue” means having a peakwavelength in the visible spectrum of 400-500 nm, and “deep blue” meanshaving a peak wavelength in the visible spectrum of 400-500 nm, where“light” and “deep” blue are distinguished by a 4 nm difference in peakwavelength. Preferably, the light blue device has a peak wavelength inthe visible spectrum of 465-500 nm, and “deep blue” has a peakwavelength in the visible spectrum of 400-465 nm. Preferred rangesinclude a peak wavelength in the visible spectrum of 610-640 nm for redand 510-550 nm for green.

To add more specificity to the wavelength-based definitions, “lightblue” may be further defined, in addition to having a peak wavelength inthe visible spectrum of 465-500 nm that is at least 4 nm greater thanthat of a deep blue OLED in the same device, as preferably having a CIEx-coordinate less than 0.2 and a CIE y-coordinate less than 0.5, and“deep blue” may be further defined, in addition to having a peakwavelength in the visible spectrum of 400-465 nm, as preferably having aCIE y-coordinate less than 0.15 and preferably less than 0.1, and thedifference between the two may be further defined such that the CIEcoordinates of light emitted by the third organic light emitting deviceand the CIE coordinates of light emitted by the fourth organic lightemitting device are sufficiently different that the difference in theCIE x-coordinates plus the difference in the CIE y-coordinates is atleast 0.01. As defined herein, the peak wavelength is the primarycharacteristic that defines light and deep blue, and the CIE coordinatesare preferred.

More generally, “light blue” may mean having a peak wavelength in thevisible spectrum of 400-500 nm, and “deep blue” may mean having a peakwavelength in the visible spectrum of 400-500 nm., and at least 4 nmless than the peak wavelength of the light blue.

In another embodiment, “light blue” may mean having a CIE y coordinateless than 0.25, and “deep blue” may mean having a CIE y coordinate atleast 0.02 less than that of “light blue.”

In another embodiment, the definitions for light and deep blue providedherein may be combined to reach a narrower definition. For example, anyof the CIE definitions may be combined with any of the wavelengthdefinitions. The reason for the various definitions is that wavelengthsand CIE coordinates have different strengths and weaknesses when itcomes to measuring color. For example, lower wavelengths normallycorrespond to deeper blue. But a very narrow spectrum having a peak at472 may be considered “deep blue” when compared to another spectrumhaving a peak at 471 nm, but a significant tail in the spectrum athigher wavelengths. This scenario is best described using CIEcoordinates. It is expected that, in view of available materials forOLEDs, that the wavelength-based definitions are well-suited for mostsituations. In any event, embodiments of the invention include twodifferent blue pixels, however the difference in blue is measured.

The first, second, third and fourth organic light emitting devices eachhave an emissive layer that includes an organic material that emitslight when an appropriate voltage is applied across the device. Anycombination of phosphorescent and fluorescent materials may be used. Inone preferred embodiment, the emissive material in each of the first andsecond organic light emitting devices is a phosphorescent material,emissive material in the third organic light emitting device is afluorescent material, and the emissive material in the fourth organiclight emitting device may be either a fluorescent material or aphosphorescent material. Preferably, the emissive material in the fourthorganic light emitting device is a phosphorescent material. In onepreferred embodiment, the emissive material in each of the first, secondand third light emitting devices is a phosphorescent material, and theemissive material in the fourth organic light emitting device may beeither a fluorescent material or a phosphorescent material. Preferably,the emissive material in the fourth organic light emitting device is aphosphorescent material.

“Red” and “green” phosphorescent devices having lifetimes andefficiencies suitable for use in a commercial display are well known andreadily achievable, including devices that emit light sufficiently closeto the various industry standard reds and greens for use in a display.Examples of such devices are provided in M. S. Weaver, V. Adamovich, B.D'Andrade, B. Ma, R. Kwong, and J. J. Brown, Proceedings of theInternational Display Manufacturing Conference, pp. 328-331 (2007); seealso B. D'Andrade, M. S. Weaver, P. B. MacKenzie, H. Yamamoto, J. J.Brown, N. C. Giebink, S. R. Forrest and M. E. Thompson, Society forInformation Display Digest of Technical Papers 34, 2, pp. 712-715(2008).

An example of a light blue fluorescent device is provided in Jiun-HawLee, Yu-Hsuan Ho, Tien-Chin Lill and Chia-Fang Wu, Journal of theElectrochemical Society, 154 (7) J226-J228 (2007). The emissive layercomprises a 9,10-bis(2′-napthyl)anthracene (ADN) host and a4,4′-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl (DPAVBi) dopant.At 1,000 cd/m², a device with this emissive layer operates with 18.0cd/A luminous efficiency and CIE 1931 (x, y)=(0.155, 0.238). Furtherexample of blue fluorescent dopant are given in “Organic Electronics:Materials, Processing, Devices and Applications”, Franky So, CRC Press,p 448-p 449 (2009). One particular example is dopant EK9, with 11 cd/Aluminous efficiency and CIE 1931 (x, y)=(0.14, 0.19). Further examplesare given in patent applications WO 2009/107596 A1 and US 2008/0203905.A particular example of an efficient fluorescent light blue system givenin WO 2009/107596 A1 is dopant DM1-1′ with host EM2′, which gives 19cd/A efficiency in a device operating at 1,000 cd/m².

An example of a light blue phosphorescent device has the structure:

ITO (80 nm)/LG101 (10 nm)/NPD (30 nm)/Compound A: Emitter A (30nm:15%)/Compound A (5 nm)/Alq₃ (40 nm)/LiF (1 nm)/Al (100 nm).

LG101 is available from LG Chem Ltd. of Korea.

Such a device has been measured to have a lifetime of 3,000 hrs frominitial luminance 1000 nits at constant de current to 50% of initialluminance, 1931 CIE coordinates of CIE (0.175, 0.375), and a peakemission wavelength of 474 nm in the visible spectrum.

“Deep blue” devices are also readily achievable, but not necessarilyhaving the lifetime and efficiency properties desired for a displaysuitable for consumer use. One way to achieve a deep blue device is byusing a fluorescent emissive material that emits deep blue, but does nothave the high efficiency of a phosphorescent device. An example of adeep blue fluorescent device is provided in Masakazu Funahashi et al.,Society for Information Display Digest of Technical Papers 47. 3, pp.709-711(2008). Funahashi discloses a deep blue fluorescent device havingCIE coordinates of (0.140, 0.133) and a peak wavelength of 460 nm.Another way is to use a phosphorescent device having a phosphorescentemissive material that emits light blue, and to adjust the spectrum oflight emitted by the device through the use of filters or microcavities.Filters or microcavities can be used to achieve a deep blue device, asdescribed in Baek-Woon Lee, Young In Hwang, Hae-Yeon Lee and Chi Woo Kimand Young-Gu Ju Society for Information Display Digest of TechnicalPapers 68.4, pp. 1050-1053 (2008), but there may be an associateddecrease in device efficiency. Indeed, the same emitter may be used tofabricate a light blue and a deep blue device, due to microcavitydifferences. Another way is to use available deep blue phosphorescentemissive materials, such as described in United States PatentPublication 2005-0258433, which is incorporated by reference in itsentirety and for compounds shown at pages 7-14. However, such devicesmay have lifetime issues. An example of a suitable deep blue deviceusing a phosphorescent emitter has the structure:

ITO (80 nm)/Compound C (30 nm)/NPD (10 nm)/Compound A: Emitter B (30nm:9%)/Compound A (5 nm)/Alq3 (30 nm)/LiF (1 nm)/Al (100 nm)

Such a device has been measured to have a lifetime of 600 hrs frominitial luminance 1000 nits at constant dc current to 50% of initialluminance, 1931 CIE coordinates of CIE: (0.148, 0.191), and a peakemissive wavelength of 462 nm.

The difference in luminous efficiency and lifetime of deep blue andlight blue devices may be significant. For example, the luminousefficiency of a deep blue fluorescent device may be less than 25% orless than 50% of that of a light blue fluorescent device. Similarly, thelifetime of a deep blue fluorescent device may be less than 25% or lessthan 50% of that of a light blue fluorescent device. A standard way tomeasure lifetime is LT₅₀ at an initial luminance of 1000 nits, i.e., thetime required for the light output of a device to fall by 50% when runat a constant current that results in an initial luminance of 1000 nits.The luminous efficiency of a light blue fluorescent device is expectedto be lower than the luminous efficiency of a light blue phosphorescentdevice, however, the operational lifetime of the fluorescent light bluedevice may be extended in comparison to available phosphorescent lightblue devices.

A device or pixel having four organic light emitting devices, one red,one green, one light blue and one deep blue, may be used to render anycolor inside the shape defined by the CIE coordinates of the lightemitted by the devices on a CIE chromaticity diagram. FIG. 5 illustratesthis point. FIG. 5 should be considered with reference to the CIEdiagrams of FIGS. 3 and 4, but the actual CIE diagram is not shown inFIG. 5 to make the illustration clearer. In FIG. 5, point 511 representsthe CIE coordinates of a red device, point 512 represents the CIEcoordinates of a green device, point 513 represents the CIE coordinatesof a light blue device, and point 514 represents the CIE coordinates ofa deep blue device. The pixel may be used to render any color inside thequadrangle defined by points 511, 512, 513 and 514. If the CIEcoordinates of points 511, 512, 513 and 514 correspond to, or at leastencircle, the CIE coordinates of devices called for by a standardgamut—such as the corners of the triangles in FIG. 4—the device may beused to render any color in that gamut.

Many of the colors inside the quadrangle defined by points 511, 512, 513and 514 can be rendered without using the deep blue device.Specifically, any color inside the triangle defined by points 511, 512and 513 may be rendered without using the deep blue device. The deepblue device would only be needed for colors falling outside of thistriangle. Depending upon the color content of the images in question,only minimal use of the deep blue device may be needed.

FIG. 5 shows a “light blue” device having CIE coordinates 513 that areoutside the triangle defined by the CIE coordinates 511, 512 and 514 ofthe red, green and deep blue devices, respectively. Alternatively, thelight blue device may have CIE coordinates that fall inside of saidtriangle.

A preferred way to operate a device having a red, green, light blue anddeep blue device, or first, second, third and fourth devices,respectively, as described herein is to render a color using only 3 ofthe 4 devices at any one time, and to use the deep blue device only whenit is needed. Referring to FIG. 5, points 511, 512 and 513 define afirst triangle, which includes areas 521 and 523. Points 511, 512 and514 define a second triangle, which includes areas 521 and 522. Points512, 513 and 514 define a third triangle, which includes areas 523 and524. If a desired color has CIE coordinates falling within this firsttriangle (areas 521 and 523), only the first, second and third devicesare used to render the color. If a desired color has CIE coordinatesfalling within the second triangle, and does not also fall within thefirst triangle (area 522), only the first, second and fourth devices areused to render color. If a desired color has CIE coordinates fallingwithin the third triangle, and does not fall within the first triangle(area 524), only the first, third and fourth, or only the second, thirdand fourth devices are used to render color.

Such a device could be operated in other ways as well. For example, allfour devices could be used to render color. However, such use may notachieve the purpose of minimizing use of the deep blue device.

Red, green, light blue and blue bottom-emission phosphorescentmicrocavity devices were fabricated. Luminous efficiency (cd/A) at 1,000cd/m² and CIE 1931 (x, y) coordinates are summarized for these devicesin Table 1 in Rows 1-4. Data for a fluorescent deep blue device in amicrocavity are given in Row 5. This data was taken from Woo-Young So etal., paper 44.3, SID Digest (2010) (accepted for publication), and is atypical example for a fluorescent deep blue device in a microcavity.Values for a fluorescent light blue device in a microcavity are given inRow 9. The luminous efficiency given here (16.0 cd/A) is a reasonableestimate of the luminous efficiency that could be demonstrated if thefluorescent light blue materials presented in patent application WO2009/107596 were built into a microcavity device. The CIE 1931 (x, y)coordinates of the fluorescent light blue device match the coordinatesof the light blue phosphorescent device.

Using device data in Table 1, simulations were performed to compare thepower consumption of a 2.5-inch diagonal, 80 dpi, AMOLED display with50% polarizer efficiency, 9.5V drive voltage, and white point (x,y)=(0.31, 0.31) at 300 cd/m². In the model, all sub-pixels have the sameactive device area. Power consumption was modeled based on 10 typicaldisplay images. The following pixel layouts were considered: RGB, wherered and green are phosphorescent and the blue device is a fluorescentdeep blue; (2) RGB1B2, where the red, green and light blue (B1) arephosphorescent and deep blue (B2) device is a fluorescent deep blue; and(3) RGB1B2, where the red and green are phosphorescent and the lightblue (B1) and deep blue (B2) are fluorescent. The average power consumedby (1) was 196 mW, while the average power consumed by (2) was 132 mW.This is a power savings of 33% compared to (1). The power consumed bypixel layout (3) was 157 mW. This is a power savings of 20% compared to(1). This power savings is much greater than one would have expected fora device using a fluorescent blue emitter as the B1 emitter. Moreover,since the device lifetime of such a device would be expected to besubstantially longer than an RGB device using only a deeper bluefluorescent emitter, a power savings of 20% in combination with a longlifetime is be highly desirable. Examples of fluorescent light bluematerials that might be used include a 9,10-bis(2′-napthyl)anthracene(ADN) host with a 4,4′-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl(DPAVBi) dopant, or dopant EK9 as described in “Organic Electronics:Materials, Processing, Devices and Applications”, Franky So, CRC Press,p 448-p 449 (2009), or host EM2′ with dopant DM1-1′ as described inpatent application WO 2009/107596 A1. Further examples of fluorescentmaterials that could be used are described in patent application US2008/0203905.

Based on the disclosure herein, pixel layout (3) is expected to resultin significant and previously unexpected power savings relative to pixellayout (1) where the light blue (B1) device has a luminous efficiency ofat least 12 cd/A. It is preferred that light blue (B1) device has aluminous efficiency of at least 15 cd/A to achieve more significantpower savings. In either case, pixel layout (3) may also providesuperior lifetime relative to pixel layout (1).

TABLE 1 Device data for bottom-emission microcavity red, green, lightblue and deep blue test devices. Rows 1-4 are phosphorescent devices.Rows 5-6 are fluorescent devices. Luminous Efficiency CIE 1931 (x, y)Red R Phosphorescent 48.1 (0.674, 0.324) Green G Phosphorescent 94.8(0.195, 0.755) Light Blue B1 Phosphorescent 22.5 (0.144, 0.148) DeepBlue B2 Phosphorescent 6.3 (0.144, 0.061) Deep Blue B2 Fluorescent 4.0(0.145, 0.055) Light Blue B1 Fluorescent 16.0 (0.144, 0.148)

Algorithms have been developed in conjunction with RGBW (red, green,blue, white) devices that may be used to map a ROB color to an RGBWcolor. Similar algorithms may be used to map an RGB color to RG B1 B2.Such algorithms, and RGBW devices generally, are disclosed in A. Arnold,T. K. Hatwar, M. Hertel, P. Kane, M. Miller, M. Murdoch, J. Spindler, S.V. Slyke, Proc. Asia Display (2004); J. P. Spindler, T. K. Hatwar, M. E.Miller, A. D. Arnold, M. J. Murdoch, P. J. Lane, J. E. Ludwicki and S.V. Slyke, SID 2005 International Symposium Technical Digest 36, 1, pp.36-39 (2005) (“Spindler”); Du-Zen Peng, Hsiang-Lun, Hsu and RyujiNishikawa. Information Display 23, 2, pp 12-18 (2007) (“Peng”); B-W.Lee, Y. I. Hwang, H-Y, Lee and C. H. Kim, SID 2008 InternationalSymposium Technical Digest 39, 2, pp. 1050-1053 (2008). RGBW displaysare significantly different from those disclosed herein because theystill need a good deep blue device. Moreover, there is teaching that the“fourth” or white device of an RGBW display should have particular“white” CIE coordinates, see Spindler at 37 and Peng at 13.

A device having four different organic light emitting devices, eachemitting a different color, may have a number of differentconfigurations. FIG. 6 illustrates some of these configurations. In FIG.6, R is a red-emitting device, G is a green-emitting device, B1 is alight blue emitting device, and B2 is a deep blue emitting device.

Configuration 610 shows a quad configuration, where the four organiclight emitting devices making up the overall device or multicolor pixelare arranged in a two by two array. Each of the individual organic lightemitting devices in configuration 610 has the same surface area. In aquad pattern, each pixel could use two gate lines and two data lines.

Configuration 620 shows a quad configuration where some of the deviceshave surface areas different from the others. It may be desirable to usedifferent surface areas for a variety of reasons. For example, a devicehaving a larger area may be run at a lower current than a similar devicewith a smaller area to emit the same amount of light. The lower currentmay increase device lifetime. Thus, using a relatively larger device isone way to compensate for devices having a lower expected lifetime.

Configuration 630 shows equally sized devices arranged in a row, andconfiguration 640 shows devices arranged in a row where some of thedevices have different areas. Patterns other than those specificallyillustrated may be used.

Other configurations may be used. For example, a stacked OLED with fourseparately controllable emissive layers, or two stacked OLEDs each withtwo separately controllable emissive layers, may be used to achieve foursub-pixels that can each emit a different color of light.

Various types of OLEDs may be used to implement various configurations,including transparent OLEDs and flexible OLEDs.

Displays with devices having four sub-pixels, in any of the variousconfigurations illustrated and in other configurations, may befabricated and patterned using any of a number of conventionaltechniques. Examples include shadow mask, laser induced thermal imaging(LITI), ink-jet printing, organic vapor jet printing (OVJP), or otherOLED patterning technology. An extra masking or patterning step may beneeded for the emissive layer of the fourth device, which may increasefabrication time. The material cost may also be somewhat higher than fora conventional display. These additional costs would be offset byimproved display performance.

A single pixel may incorporate more than the four sub-pixels disclosedherein, possibly with more than four discrete colors. However, due tomanufacturing concerns, four sub-pixels per pixel is preferred.

An architecture and method is provided for constructing asuperposition/spatial color synthesis OLED pixel architecture for anRGB1B2 display. The RG sub-pixels are located in a first device planeseparate from a second device plane that includes at least one of the B1or B2 blue sub-pixels. At least one of the device planes issubstantially transparent i.e. TOLEDs (transparent OLEDs). Thisarchitecture has many potential advantages over a conventional side byside pixel arrangement. It allows for greater fill factor for some orall devices of a particular color, which may be used to increase thelifetime of the weakest devices, such as the blue devices. For example,the deep blue device, if used as frequently as the other devices, may bethe “weakest” device if considered in isolation, i.e., if the lifetimeof the device is measured for continuous usage. However, manyembodiments of an RGB1B2 display are specifically designed to minimizeuse of the B2 sub-pixel, such that the B1 sub-pixel may be the weakestdevice when factors such as average use are considered in addition todevice lifetime in isolation.

As used herein, “fill factor” refers to the ratio of the area ofemissive device surface to an outline of the area that includes emissivedevice surface. Fill factor is intended to quantify the inactive areabetween devices, where a high fill factor corresponds to a low inactivearea between devices. Fill factor is also affected by any device areathat does not emit light that reaches a viewer for whatever reason, suchas placement of thin film transistors that are not transparent. Thus,any inactive panel area around the periphery of a panel with no devicesis not considered in the calculation of fill factor as used herein.

The 2 planes of OLED sub-pixels can be constructed in a variety of ways.For example the first and second device planes could be constructed on 2separate backplanes and then be attached together where one of thebackplanes is substantially transparent. Alternatively the two deviceplanes could be constructed on top of each other fabricated over onebackplane using stacked OLED (SOLED) technology where the 2 planes areindividually addressable. One way to fabricate two device planes one ontop of the other over one backplane is to use a fine metal mask andvapor thermal evaporation (VTE) to fabricate the first device plane.

Embodiments of the invention may be used for displays capable ofdisplaying images. Embodiments of the invention may be used for generalillumination purposes, where the light source may or may not be colortunable. While a light source that produces white light is a preferredembodiment, other colors of light may also be produced.

A first device is provided. The device includes a plurality of pixels,wherein each pixel includes an R sub-pixel, a G sub-pixel, a B1sub-pixel and a B2 sub-pixel. Each R sub-pixel comprises a first organiclight emitting device that emits light having a peak wavelength in thevisible spectrum of 580-700 nm, further comprising a first emissivelayer having a first emitting material. Each G sub-pixel comprises asecond organic light emitting device that emits light having a peakwavelength in the visible spectrum of 500-580 nm, further comprising asecond emissive layer having a second emitting material. Each B1sub-pixel comprises a third organic light emitting device that emitslight having a peak wavelength in the visible spectrum of 400-500 nm,further comprising a third emissive layer having a third emittingmaterial. Each B2 sub-pixel comprises a fourth organic light emittingdevice that emits light having a peak wavelength in the visible spectrumof 400 to 500 nm, further comprising a fourth emissive layer having afourth emitting material. The third emitting material is different fromthe fourth emitting material. The peak wavelength in the visiblespectrum of light emitted by the fourth organic light emitting device isat least 4 nm less than the peak wavelength in the visible spectrum oflight emitted by the third organic light emitting device.

The first device includes a first device plane and a second deviceplane. The first device plane comprises a plurality of the first organiclight emitting device and a plurality of the second organic lightemitting device. The second device plane comprises a plurality of atleast one of the third organic light emitting device and the fourthorganic light emitting device. The planes of the first and second deviceplanes are parallel. The second device plane is transposed from thefirst device plane in a direction perpendicular to the planes of thefirst and second device planes. The first and second device planes aresuperposed.

In one embodiment, the second device plane comprises a plurality of thethird organic light emitting device, and a plurality of the fourthorganic light emitting device.

In one embodiment, the first device plane comprises a plurality of thefirst organic light emitting device, a plurality of the second organiclight emitting device, and a plurality of the third organic lightemitting device. The second device plane comprises a plurality of thefourth organic light emitting device.

In one embodiment, the first device plane comprises a plurality of thefirst organic light emitting device, a plurality of the second organiclight emitting device, and a plurality of the fourth organic lightemitting device. The second device plane comprises a plurality of thethird organic light emitting device.

Preferably, at least one of the first and second device planes each hasa fill factor of at least 30%.

Preferably, the first device is configured such that the first deviceplane is closer to a viewing direction than the second device plane.

The first device may be a display panel. The first device may be aconsumer device.

In one preferred embodiment, the first, second and third emittingmaterials are phosphorescent, and the fourth emitting material isfluorescent. In one preferred embodiment, the first and second emittingmaterials are phosphorescent, and the third and fourth emittingmaterials are fluorescent. A variety of other combinations of emittingmaterial types may be used, such as where the first, second, third andfourth emitting materials are phosphorescent.

FIG. 7 shows two different configurations providing two device planes. Afirst configuration 710 shows a first device plane 721 fabricated on afirst substrate (or backplane) 720. A second device plane 731 isfabricated on a second substrate 730. The first and second substratesmay be attached by any conventional method, such as lamination.

A second configuration 750 shows a first substrate 760 having first andsecond device planes 761 and 762 stacked thereon in that order.

FIG. 8 shows a first way to split R, G, B1 and B2 devices between twodevice planes. A first device plane 810 has R and G sub-pixels disposedthereon. A second device plane 820 has B1 and B2 sub-pixels disposedthereon. First device plane 810 and second device plane 820 of FIG. 8may correspond to first device plane 721 and second device plane 731 ofFIG. 7, respectively. Alternatively, first device plane 810 and seconddevice plane 820 of FIG. 8 may correspond to second device plane 731 andfirst device plane 721 of FIG. 7, respectively. First device plane 810and second device plane 820 of FIG. 8 may correspond to first deviceplane 761 and second device plane 762 of FIG. 7, respectively.Alternatively, first device plane 810 and second device plane 820 ofFIG. 8 may correspond to second device plane 762 and first device plane761 of FIG. 7, respectively.

FIG. 9 shows a second way to split R, G, B1 and B2 devices between twodevice planes. A first device plane 910 has R, G and B1 sub-pixelsdisposed thereon. A second device plane 920 has B2 sub-pixels disposedthereon. First device plane 910 and second device plane 920 of FIG. 9may correspond to first device plane 721 and second device plane 731 ofFIG. 7, respectively. Alternatively, first device plane 910 and seconddevice plane 920 of FIG. 9 may correspond to second device plane 731 andfirst device plane 721 of FIG. 7, respectively. First device plane 910and second device plane 920 of FIG. 9 may correspond to first deviceplane 761 and second device plane 762 of FIG. 7, respectively.Alternatively, first device plane 910 and second device plane 920 ofFIG. 9 may correspond to second device plane 762 and first device plane761 of FIG. 7, respectively.

FIG. 10 shows a third way to split R, G, B1 and B2 devices between twodevice planes. A first device plane 1010 has R, G and B2 sub-pixelsdisposed thereon. A second device plane 1020 has B1 sub-pixels disposedthereon. First device plane 1010 and second device plane 1020 of FIG. 10may correspond to first device plane 721 and second device plane 731 ofFIG. 7, respectively. Alternatively, first device plane 1010 and seconddevice plane 1020 of FIG. 10 may correspond to second device plane 731and first device plane 721 of FIG. 7, respectively. First device plane1010 and second device plane 1020 of FIG. 10 may correspond to firstdevice plane 761 and second device plane 762 of FIG. 7, respectively.Alternatively, first device plane 1010 and second device plane 1020 ofFIG. 9 may correspond to second device plane 762 and first device plane761 of FIG. 7, respectively.

FIG. 11 shows a specific device architecture 1100 for a R, G, B1 and B2devices split between two device planes having a common electrodebetween the two device planes. In FIGS. 11 and 12, where no arrow orconnecting line is present, a reference numeral refers to the layer onwhich it appears. The architecture includes anodes 1110 for each of anR, G and B2 device that are individually addressable and electricallyseparated by insulating grid 1115. Electronics that are most oftenlocated in the substrate, such as transistors and contact pads for eachanode, are not shown. An organic hole transport layer 1120 common toeach of the R, G and B2 devices is disposed over anodes 1110.Individually patterned organic emissive layers 1131, 1132 and 1133, forR, G and B2 devices, respectively, are disposed over organic holetransport layer 1120. Individually patterned organic emissive layers1131, 1132 and 1133 include different emissive materials suitable foruse with R, G and B2 devices, respectively An organic electron transportlayer 1140 common to each of the R, G and B2 devices is disposed overemissive layers 1131, 1132 and 1133. An electrode 1150 is disposed overorganic electron transport layer 1140, and is also connected to contactpad 1117. Electrode 1150 acts as a cathode for the R, G and B2 devices,and as an anode for the B1 device. Organic emissive layer 1160, whichincludes an emissive material suitable for use with a B1 device, isdisposed over electrode 1150. Cathode 1170 is disposed over organicemissive layer 1160.

FIG. 12 shows a specific device architecture 1200 for a R, G, B1 and B2devices split between two device planes having a passivation layer 1280between the two device planes. The architecture includes anodes 1210 foreach of an R, G and B2 device that are individually addressable andelectrically separated by insulating grid 1215. Electronics that aremost often located in the substrate, such as transistors and contactpads for each anode, are not shown. An organic hole transport layer 1220common to each of the R, G and B2 devices is disposed over anodes 1210.Individually patterned organic emissive layers 1231, 1232 and 1233, forR, G and B2 devices, respectively, are disposed over organic holetransport layer 1220. Individually patterned organic emissive layers1231, 1232 and 1233 include different emissive materials suitable foruse with R, G and B2 devices, respectively An organic electron transportlayer 1240 common to each of the R, G and B2 devices is disposed overemissive layers 1231, 1232 and 1233. Residual parts of organic hole andtransport layers 1220 and 1240 are disposed to the right of organicemissive layer 1233. An electrode 1250 is disposed over organic electrontransport layer 1240, and is also connected to the grid. Electrode 1250acts as a cathode for the R, G and B2 devices. A passivation layer 1280separates the B1 device from the R, G and B2 devices. Organic emissivelayer 1260, which includes an emissive material suitable for use with aB I device, is disposed between anode 1255 and cathode 1270. Anode 1255is connected to grid 1261. Cathode 1270 is connected to contact pad1217.

Each of the organic “layers” in device architectures 1100 and 1200 mayrepresent multiple organic layers that are patterned similarly, forexample by being deposited through the same shadow mask. Thus, forexample, hole transport layers 1120 and 1220 may include a holeinjection layer, a hole transport layer, and an electron blocking layer.Emissive layers 1160 and 1260 may include all of the layers of an OLEDdevice, including injection layers, transport layers and blockinglayers. The criteria for labeling separate layers in FIGS. 11 and 12 iswhether the layers are adjacent and similarly patterned, such that theycould, for example, be deposited sequentially through the same shadowmask.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. Many of the specificarrangements of sub-pixels may be modified without deviating from thespirit of the invention. The present invention as claimed may thereforeincludes variations from the particular examples and preferredembodiments described herein, as will be apparent to one of skill in theart. It is understood that various theories as to why the inventionworks are not intended to be limiting.

The invention claimed is:
 1. A first device, comprising: a plurality ofpixels, wherein each pixel includes an R sub-pixel, a G sub-pixel, a B1sub-pixel and a B2 sub-pixel, wherein: each R sub-pixel comprises afirst organic light emitting device that emits light having a peakwavelength in the visible spectrum of 580-700 nm, further comprising afirst emissive layer having a first emitting material; each G sub-pixelcomprises a second organic light emitting device that emits light havinga peak wavelength in the visible spectrum of 500-580 nm, furthercomprising a second emissive layer having a second emitting material;each B1 sub-pixel comprises a third organic light emitting device thatemits light having a peak wavelength in the visible spectrum of 400-500nm, further comprising a third emissive layer having a third emittingmaterial; each B2 sub-pixel comprises a fourth organic light emittingdevice that emits light having a peak wavelength in the visible spectrumof 400 to 500 nm, further comprising a fourth emissive layer having afourth emitting material; the third emitting material is different fromthe fourth emitting material; and the peak wavelength in the visiblespectrum of light emitted by the fourth organic light emitting device isat least 4 nm less than the peak wavelength in the visible spectrum oflight emitted by the third organic light emitting device; a first deviceplane comprising a plurality of the first organic light emitting deviceand a plurality of the second organic light emitting device, wherein thefirst device plane is parallel to the plane of the plurality of thefirst organic light emitting device and a plurality of the secondorganic light emitting device; a second device plane comprising aplurality of at least one of the third organic light emitting device andthe fourth organic light emitting device, wherein the second deviceplane is parallel to the Diane of the at least one of the third organiclight emitting device and fourth organic light emitting device; whereinthe planes of the first and second device planes are parallel, thesecond device plane is transposed from the first device plane in adirection perpendicular to the planes of the first and second deviceplanes, and the first and second device planes are superposed.
 2. Thefirst device of claim 1, wherein the second device plane comprises aplurality of the third organic light emitting device, and a plurality ofthe fourth organic light emitting device.
 3. The first device of claim1, wherein the first device plane comprises a plurality of the firstorganic light emitting device, a plurality of the second organic lightemitting device, and a plurality of the third organic light emittingdevice, and the second device plane comprises a plurality of the fourthorganic light emitting device.
 4. The first device of claim 1, whereinthe first device plane comprises a plurality of the first organic lightemitting device, a plurality of the second organic light emittingdevice, and a plurality of the fourth organic light emitting device, andthe second device plane comprises a plurality of the third organic lightemitting device.
 5. The first device of claim 1, wherein at least one ofthe first and second device planes has a fill factor of at least 30%. 6.The first device of claim 1, wherein the first device is configured suchthat the first device plane is closer to a viewing direction than thesecond device plane.
 7. The first device of claim 1, wherein the firstdevice is a display panel.
 8. The first device of claim 1, wherein thefirst device is a consumer device.
 9. The first device of claim 1,wherein the first, second and third emitting materials arephosphorescent, and the fourth emitting material is fluorescent.
 10. Thefirst device of claim 1, wherein the first, second, third and fourthemitting materials are phosphorescent.
 11. The first device of claim 1,wherein the first and second materials are phosphorescent, and the thirdand fourth emitting materials are fluorescent.